Oculomotor and Pupillary Markers of Visuospatial Mental Imagery in Aphantasia and Typical Imagery

Our eyes engage not only in visual perception but also in visual mental imagery, mimicking perceptual processes without external stimuli. Mental imagery vividness varies along a spectrum, with aphantasia at the lower extreme, where individuals report a reduced or absent ability to visualize voluntarily. However, they can recall visual information from memory. For example, they can state from memory that Bordeaux is left of Paris on a map of France while denying any mental imagery. What cognitive mechanisms underlie this dissociation? Some theories suggest aphantasia stems from impaired image generation, while others propose it reflects a lack of metacognitive awareness of visual mental imagery.This study examines oculomotor and pupillometry patterns in typical imagery and aphantasia during a mental exploration task involving an imagined map of France. We test four competing hypotheses: (i) reduced eye movements in aphantasia due to absent mental images, (ii) increased exploratory eye movements as a sensorimotor compensatory strategy, (iii) typical eye movements with impaired metacognitive access, or (iv) heterogeneous eye movement patterns. We also predict greater pupil dilation in aphantasia, indicating increased cognitive load. By distinguishing between these possibilities, this study will contribute to the understanding of the cognitive mechanisms underlying aphantasia.